Somehow, without moving to a new house my garden has become a zone warmer. What was once just a Zone 9A garden is now a wonderful 9B garden. What does this mean for me personally? It means that I now have access to 2,023 plants at Annie's Annuals that will grow in my backyard. Yesterday there were only 1,925 plants I could grow. So there's that.
This change has been a long time coming (22 years since the last update). In the meantime, most people who care about this sort of thing had already adjusted their zones in their own mind or switched over to a different system such as the Sunset Western Garden zones which looks at your location's overall climate including summer highs, length of the growing season, rainfall and humidity and not just winter lows like the USDA chart does.
I don't really see this making a huge difference in the way I garden. To me, it's more of an acknowledgement on the part of the USDA that their previous map was so 90's and was overdue for a makeover. It might also say something about global climate change . . . but I'll let the USDA speak for itself on that "hot" button topic.
I'd love to hear if anyone had a more signficant change in their official zone rating and what that means to them as a gardener, if anything.
